I have a couple nova chucks. ie supernova and titan

With regular jaw changes I've noticed that the screws have worn and
need to be replaced.

Woodcraft wants $12 for a set of 8 screws and craft supply wants $4.

I tried a local hardware store and they had similar screws but the
heads looked much larger.

Anyone know were I can buy these screws at less than 50 cents a piece?